Shader "MyShader/BackBlur" {
	Properties
	{
	[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
		   _Color("Main Color", Color) = (1,1,1,1)
	_Size("Size", Range(0, 20)) = 1
	}
		Category{

			   // We must be transparent, so other objects are drawn before this one.  
			   Tags {
							  "Queue" = "Transparent"
							  "IgnoreProjector" = "True"
							  "RenderType" = "Transparent"
							  "PreviewType" = "Plane"
							  "CanUseSpriteAtlas" = "True"
					  }


			   SubShader {

			   // Horizontal blur  
			   GrabPass {
				   Tags { "LightMode" = "Always" }
			   }
			   Pass {
				   Tags { "LightMode" = "Always" }
				   Name "BackBlurHor"
				   CGPROGRAM
				   #pragma vertex vert  
				   #pragma fragment frag  
				   #pragma fragmentoption ARB_precision_hint_fastest  
				   #include "UnityCG.cginc"  

				   struct appdata_t {
					   float4 vertex : POSITION;
					   float2 texcoord : TEXCOORD0;
										 float4 color    : COLOR;
				   };

				   struct v2f {
					   float4 vertex : POSITION;
					   float4 uvgrab : TEXCOORD0;
										 float4 color    : COLOR;
				   };

				   v2f vert(appdata_t v) {
					   v2f o;
					   o.vertex = UnityObjectToClipPos(v.vertex);
					   #if UNITY_UV_STARTS_AT_TOP  
					   float scale = -1.0;
					   #else  
					   float scale = 1.0;
					   #endif  
					   o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) *  0.5;
					   o.uvgrab.zw = o.vertex.zw;
										 o.color = v.color;
					   return o;
				   }

				   sampler2D _GrabTexture;
				   float4 _GrabTexture_TexelSize;
							  float4 _MainTex_TexelSize;
				   float _Size;
				   uniform float4 _Color;
				   // static float GaussianKernel[9] = {
				   //     0.05, 0.09, 0.12,
				   //     0.15, 0.18, 0.15,
				   //     0.12, 0.09, 0.05
				   // };
				   // static float GaussianKernel[19] = {
				   //     0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09,
				   //     0.1,
				   //     0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01,
				   // };
				   // static float GaussianKernelD[19] = {
				   //     -9.0, -8.0, -7.0, -6.0, -5.0, -4.0, -3.0, -2.0, -1.0,
				   //     0.0,
				   //     +1.0, +2.0, +3.0, +4.0, +5.0, +6.0, +7.0, +8.0, +9.0,
				   // };
				   half4 GrabPixel(v2f i, float weight, float kernelx) {
					   if (i.uvgrab.x == 0 && i.uvgrab.y == 0) {
						   kernelx = 0;
					   }
					   return tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x + _GrabTexture_TexelSize.x*kernelx*_Size, i.uvgrab.y, i.uvgrab.z, i.uvgrab.w))) * weight;
				   }
				   half4 frag(v2f i) : COLOR {
						  half4 sum = half4(0,0,0,0);
						  // #define GRABPIXEL(weight, kernelx) tex2Dproj(_GrabTexture,  UNITY_PROJ_COORD(float4(i.uvgrab.x + _GrabTexture_TexelSize.x * kernelx*_Size, i.uvgrab.y,  i.uvgrab.z, i.uvgrab.w))) * weight

						  sum += GrabPixel(i, 0.05, -4.0);
						  sum += GrabPixel(i, 0.09, -3.0);
						  sum += GrabPixel(i, 0.12, -2.0);
						  sum += GrabPixel(i, 0.15, -1.0);
						  sum += GrabPixel(i, 0.18,  0.0);
						  sum += GrabPixel(i, 0.15, +1.0);
						  sum += GrabPixel(i, 0.12, +2.0);
						  sum += GrabPixel(i, 0.09, +3.0);
						  sum += GrabPixel(i, 0.05, +4.0);
						  // sum += GrabPixel(i, 0.01, -9.0);
						  // sum += GrabPixel(i, 0.02, -8.0);
						  // sum += GrabPixel(i, 0.03, -7.0);
						  // sum += GrabPixel(i, 0.04, -6.0);
						  // sum += GrabPixel(i, 0.05, -5.0);
						  // sum += GrabPixel(i, 0.06, -4.0);
						  // sum += GrabPixel(i, 0.07, -3.0);
						  // sum += GrabPixel(i, 0.08, -2.0);
						  // sum += GrabPixel(i, 0.09, -1.0);
						  // sum += GrabPixel(i, 0.10,  0.0);
						  // sum += GrabPixel(i, 0.09, +1.0);
						  // sum += GrabPixel(i, 0.08, +2.0);
						  // sum += GrabPixel(i, 0.07, +3.0);
						  // sum += GrabPixel(i, 0.06, +4.0);
						  // sum += GrabPixel(i, 0.05, +5.0);
						  // sum += GrabPixel(i, 0.04, +6.0);
						  // sum += GrabPixel(i, 0.03, +7.0);
						  // sum += GrabPixel(i, 0.02, +8.0);
						  // sum += GrabPixel(i, 0.01, +9.0);
						  float4 col5 = tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(i.uvgrab));
											float decayFactor = 1.0f;
											if (i.uvgrab.x == 0 && i.uvgrab.y == 0) {
												   decayFactor = 0;
											}
											sum = lerp(col5, sum, decayFactor) * i.color *  _Color;

						  return sum;
					  }
					  ENDCG
				  }
			   // Vertical blur  
			   GrabPass {
				   Tags { "LightMode" = "Always" }
			   }
			   Pass {
				   Tags { "LightMode" = "Always" }
				   Name "BackBlurVer"
				   CGPROGRAM
				   #pragma vertex vert  
				   #pragma fragment frag  
				   #pragma fragmentoption ARB_precision_hint_fastest  
				   #include "UnityCG.cginc"  

				   struct appdata_t {
					   float4 vertex : POSITION;
					   float2 texcoord: TEXCOORD0;
										 float4 color    : COLOR;
				   };

				   struct v2f {
					   float4 vertex : POSITION;
					   float4 uvgrab : TEXCOORD0;
										 float4 color    : COLOR;
				   };

				   v2f vert(appdata_t v) {
					   v2f o;
					   o.vertex = UnityObjectToClipPos(v.vertex);
					   #if UNITY_UV_STARTS_AT_TOP  
					   float scale = -1.0;
					   #else  
					   float scale = 1.0;
					   #endif  
					   o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) *  0.5;
					   o.uvgrab.zw = o.vertex.zw;
										 o.color = v.color;
					   return o;
				   }

				   sampler2D _GrabTexture;
				   float4 _GrabTexture_TexelSize;
				   float _Size;
				   uniform float4 _Color;
				   half4 GrabPixel(v2f i, float weight, float kernely) {
					   if (i.uvgrab.x == 0 && i.uvgrab.y == 0) {
						   kernely = 0;
					   }
					   return tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x,  i.uvgrab.y + _GrabTexture_TexelSize.y*kernely*_Size, i.uvgrab.z, i.uvgrab.w))) * weight;
				   }

				   half4 frag(v2f i) : COLOR {
					   half4 sum = half4(0,0,0,0);
					   // #define GRABPIXEL(weight,kernely) tex2Dproj( _GrabTexture,  UNITY_PROJ_COORD(float4(i.uvgrab.x, i.uvgrab.y + _GrabTexture_TexelSize.y * kernely*_Size,  i.uvgrab.z, i.uvgrab.w))) * weight  

					   sum += GrabPixel(i, 0.05, -4.0);
					   sum += GrabPixel(i, 0.09, -3.0);
					   sum += GrabPixel(i, 0.12, -2.0);
					   sum += GrabPixel(i, 0.15, -1.0);
					   sum += GrabPixel(i, 0.18,  0.0);
					   sum += GrabPixel(i, 0.15, +1.0);
					   sum += GrabPixel(i, 0.12, +2.0);
					   sum += GrabPixel(i, 0.09, +3.0);
					   sum += GrabPixel(i, 0.05, +4.0);
					   // sum += GrabPixel(i, 0.01, -9.0);
					   // sum += GrabPixel(i, 0.02, -8.0);
					   // sum += GrabPixel(i, 0.03, -7.0);
					   // sum += GrabPixel(i, 0.04, -6.0);
					   // sum += GrabPixel(i, 0.05, -5.0);
					   // sum += GrabPixel(i, 0.06, -4.0);
					   // sum += GrabPixel(i, 0.07, -3.0);
					   // sum += GrabPixel(i, 0.08, -2.0);
					   // sum += GrabPixel(i, 0.09, -1.0);
					   // sum += GrabPixel(i, 0.10,  0.0);
					   // sum += GrabPixel(i, 0.09, +1.0);
					   // sum += GrabPixel(i, 0.08, +2.0);
					   // sum += GrabPixel(i, 0.07, +3.0);
					   // sum += GrabPixel(i, 0.06, +4.0);
					   // sum += GrabPixel(i, 0.05, +5.0);
					   // sum += GrabPixel(i, 0.04, +6.0);
					   // sum += GrabPixel(i, 0.03, +7.0);
					   // sum += GrabPixel(i, 0.02, +8.0);
					   // sum += GrabPixel(i, 0.01, +9.0);
										 float4 col5 = tex2Dproj(_GrabTexture,  UNITY_PROJ_COORD(i.uvgrab));
										 float decayFactor = 1.0f;
										 if (i.uvgrab.x == 0 && i.uvgrab.y == 0) {
												decayFactor = 0;
										 }
										 sum = lerp(col5, sum, decayFactor) * i.color *  _Color;

					   return sum;
				   }
				   ENDCG
			   }
		   }
		   }
}
